Place scraped fish in a bowt. Add half of ginger. garlic. lemon grass. turmeric. chili. salt. sugar and knead fish and press repeating this several times. With wet fingers. take a tablespoon of the fish and make into a ball. Do this till fish is exhausted.

Bring the water to a boil. Place fish balls in water and let boil for 10 minutes. Strain the balls and set aside the water.

Cook the oil. When cooked. add the rest of the ginger. garlic. lemon grass. turmeric. chili to oil till light golden. Add the strained fish balls. Add fish sauce. sugar. tomato puree and the water which had been set aside. Add the coconut milk. Keep boiling for 10 minutes. Sprinkle cut coriander leaves. Adjust salt and sugar to taste. Feather-back fish curry is ready to serve.